1. Field of the Invention
The present invention is concerned with novel centrally-acting analgesic agents, i.e., agents acting on opiate receptors within the central nervous system to produce potent and profound analgesia.
The most widely used centrally-acting analgesic continues to be morphine. This drug, however, has serious drawbacks as the result of certain pronounced side effects. Not only does use or morphine usually lead to physiological and psychological dependency, but morphine is a respiratory depressant as well.
Thus, there has been a continuous search for a centrally-acting analgesic with the potency of morphine, but without its dangerous side effects. For example, many analgesic agents based on the morphine model have been prepared. One of the best known of these is meperidine. While this drug was originally thought to be non-addicting, it was soon found to have dangerous addiction liability.
Other centrally-acting analgesics include the class of compounds known as the benzomorphans. Pentazocine, phenazocine, cyclazocine, ketocyclazocine, and ethylketocycloazocine are some of the better known members of this class of compounds. However, as with other centrally-acting analgesics developed heretofore, the benzomorphans also have undesirable addiction qualities.
2. Brief Description of the Prior Art
Robinson et. al., U.S. Pat. Nos. 3,700,734; 3,514,463; 3,513,169; and 3,499,906 describe benzomorphan derivatives having analgesic activity.
Freed et. al., U.S. Pat. Nos. 3,836,670; 4,001,331; and 4,076,953 describe benzobicycloalkane amines for inducing analgesia.
Co-pending U.S. Ser. No. 117,701, filed Feb. 19, 1980, describes derivatives of 2-hydroxy-6,9-methano-11-amino-5,6,7,8,9,10-hexahydrobenzocyclooctene.
However, none of the compounds disclosed in any of the above would suggest the novel compounds of the present invention to a person of ordinary skill in the art.